The present invention relates to a method and a production plant for producing aromatic hydrocarbons by a catalytic aromatic production reaction.
Priority is claimed on Japanese Patent Application No. 2010-72373, filed Mar. 26, 2010, the content of which is incorporated herein by reference.
Methods for producing aromatic hydrocarbons such as BTX (benzene, toluene and xylene) from a feedstock oil such as a light cycle oil (hereinafter also abbreviated as “LCO”) obtained from a fluid catalytic cracking (hereinafter also abbreviated as “FCC”) apparatus, or a light naphtha or heavy naphtha or the like obtained from a crude oil distillation apparatus, using a catalytic aromatic production reaction that employs an aromatic production catalyst are already well known. These production systems generally employ a fixed bed system (see Patent Document 1), a moving bed system (see Patent Document 2) or a fluidized bed system (see Patent Document 3).
However, feedstock oil such as an LCO obtained from an FCC apparatus, or a light naphtha or heavy naphtha obtained from a crude oil distillation apparatus usually contain a sulfur fraction, and therefore the feedstock oil must be subjected to a preliminary hydrotreatment. Also, the produced crude aromatic fraction including a large amount of BTX contains a sulfur fraction and olefins, and therefore the crude aromatic fraction must be subjected to a hydrotreatment.
However, because hydrogen is required for this type of hydrotreatment, a separate hydrogen production plant must be provided in addition to the aromatic hydrocarbon production plant. As a result, the overall system containing the aromatic hydrocarbon production plant becomes more complex, increasing the production costs for the aromatic hydrocarbons.